1. Field of the Invention.
This invention generally relates to application of closures to containers and, more particularly, to apparatus for restraining a container against rotation during the application of a closure to the container. It is particularly useful for restraining rotation during pre-tightening and final tightening of screw-on closures.
2. Description of the Prior Art.
Innovation in the bottling industry is very dependent on the ready availability of machinery for processing new types of containers and closures. For years, the crown was the dominant closure employed. A different type of closure was then developed, which comprised a cap shell of aluminum which was inserted over the threaded neck end of the container and then secured in place by rolling threads in situ into the walls of the cap shell. Such closures are commonly called roll-on caps.
The roll on cap necessarily required a completely new applicating machine because not only was an axial force necessary to hold the closure in place on the bottle neck and effect a seal between the closure liner and the end of the bottle neck but, concurrently, a rotating movement had to be imparted to the thread forming rollers. There was no practical way that a conventional crown-type applicating machine could be modified to apply the new style roll-on closures and, as a result, the adoption of the new closure proceeded very slowly. It did proceed, however, and now machinery for applying roll-on closures is common.
In recent years, there have been significant developments in plastic technology making the utilization of a threaded plastic closure completely feasible for use in the carbonated beverage field. For example, a threaded closure of the type shown in U.S. Pat. Nos. 3,987,921 and 4,016,996 has been shown to be commercially practicable, and an economically desirable change for the bottler to adopt if applicating machinery was available to assemble the plastic closure to the bottle neck.
Since the plastic closure required a concurrent application of an axial force to the top panel of the closure with a rotation of the closure relative to the bottle neck, it was desirable to utilize existing closure applicating machines for effecting the assembly of aluminum shells to bottle necks to apply the new style plastic closure, and thus minimize the new investment required by the bottler. This was accomplished by a number of modifications of capping heads which may be applied to existing roll-on closure applicating machines.
Some of the roll-on type applicating machines do not incorporate a sufficient rotational movement of the capping head as it approaches its lowermost position relative to the bottle to effect the complete threading of a closure onto the threaded bottle neck. Therefore, pre-tightening mechanisms were developed, which partially apply a threaded closure on the threaded neck of a bottle prior to a closure being engaged by the applicating head.
In addition, problems were encountered in keeping the container from rotating during the final closure tightening process when sufficient torque is applied to seal the closure on the neck, yet allowing the closure to be manually removed by the ultimate consumer.
Restraint systems to control container rotation have been added on to application machinery to press against containers from the outside during the final tightening of the closure. However, these systems have not been satisfactory since the containers are already turning when they reach the system and it has to apply braking torque. It takes on undesirable amount of friction and pressure to stop a container from rotating after it is already turning, which may damage container labels or the containers themselves and/or interfere with the application of the correct amount of torque to seal the closure on the neck. Similar problems are met when the turntable surfaces are covered with friction material to stop container rotation.